Spinning solutions of polyvinyl chloride in mixtures of trichloroethylene and nitromethane



SPINNING SOLUTIONS OF POLYVINYL CHLO- RIDE IN MIXTURES OF TRICHLOROETHYLENE AND NITROMETHANE Enrico Cernia and Alberto Bonvicini, Terni, Italy, assignors to Montecatini Societi: Generale per llndustria Mineraria e Chimica, Milan, Italy, a corporation of Italy No Drawing. Filed Feb. 25, 1958, Ser. No. 717,305

Claims priority, application Italy Feb. 28, 1957 2 Claims. (Cl. 260-624) The present invention relates to solvents for vinyl chloride polymers.

Polyvinyl chloride is used for making textile fibers from spinning solutions obtained by dissolving the polymer in suitable solvents or solvent mixtures. The solvent generally used for polyvinyl chloride consists of a mixture of equal portions of carbon disulphide and acetone although this mixture has the disadvantage of being toxic and having a low flash point.

Other solvents can be employed for this purpose. However, they are characterized by either high boiling points, such as dimethyl formamide, dioxane, chlorobenzene, etc., and/or by high costs, such as tetrahydrofurane, dioxane, dimethyl formamide and others. The present invention, which eliminates or reduces the aforementioned shortcomings, is based on that fact that mixtures of trichloroethylene and nitromethane at variable ratios, but particularly a mixture containing 80 parts of trichloroethylene and 20 parts of nitromethane, can be profitably used for the so-called dry spinning of polyvinyl chloride.

Our discovery that these binary mixtures can be employed as suitable spinning solution solvents for polyvinyl chloride was entirely unexpected since the two components, taken separately, are not solvents for this polymer.

The solvent mixture according to the present invention possesses the principal properties required of a spinning solution solvent of polyvinyl chloride, namely, a low boiling point, low toxicity and low costs.

As stated above, we have found that the most suitable mixture for this purpose consists of 80 parts trichloroethylene and 20 parts nitromethane. These two compounds form an azeotropic mixture of constant boiling point at 814 C.

The following two examples are presented to illustrate, but in no way limit, the present invention:

Example 1 A trichloroethylene-nitromethane mixture containing 80 parts of trichloroethylene and 20 parts of nitromethane is prepared at room temperature.

The mixture thus obtained is employed for preparing a spinning solution containing 20% of polyvinyl chloride having a Fikentscher value K=68.2 at a temperature from 60 to 65 C.

After extruding this solution through a spinneret having 38 holes, each 80 microns in diameter, the solvent is evaporated within the drying column and recovered. During the operation, the spinning head is kept at 80 C. while the temperature of the driving column is maintained at 120 C.

3,036,026 Patented May 22, 1962 The yarn obtained in this manner is stretched at a ratio of 1:4, and is then twisted and thermally stabilized at C. The serimetrical characteristics of the yarn thus obtained are as follows: tensile strength, 2.65 g./ den.; elongation, 16.91%.

Example 2 A mixture prepared by mixing 20 parts of nitromethane with parts of trichloroethylene is employed to prepare a spinning solution containing 21% polyvinyl chloride, whose molecular size is characterized by a Fikentscher value K=65. This solution is prepared by stirring for four hours at 6870 C.

It is thereafter spun through a spinneret having 38 holes, each 80 microns in diameter.

During the spinning operation, the solution is kept in a jacketed tank, heated to about 80 C. by means of water circulating in the jacket. The spinning head is kept at 77 C.; the spinneret pressure is 31 kg./mm. the temperature of the drying column is maintained at 119 C.

After the yarn has been collected and stretched in boiling water at a ratio of 1:4.2, it is twisted and thermally stabilized at 65 C. The serimetrical characteristics of the yarn are as follows: tensile strength, 2.3 g./den.; elongation, 26%.

In the examples, two preferred modes of operation have been illustrated, but it is understood that either the proportions of the two components of the spinning solvents or the temperature can vary over wide limits without departing from the spirit or scope of the present invention. For example, a useful spinning solution solvent for polyvinylchloride is obtained by mixing 60 parts of nitromethane with 40 parts of trichloroethylene.

We claim:

1. A spinning solution for vinyl chloride polymers comprising polyvinyl chloride dissolved in a mixture of trichloroethylene and nitromethane., at a ratio ranging from 4 parts trichloroethylene to 1 part nitromethane, to 2 parts trichloroethylene to 3 parts nitromethane.

2. A spinning solution for vinyl chloride polymers comprising polyvinyl chloride dissolved in a mixture consisting of 4 parts trichloroethylene to 1 part nitromethane.

References Cited in the file of this patent UNITED STATES PATENTS 2,161,766 Rugeley June 6, 1939 2,271,581 Bogin Feb. 3, 1942 2,366,414 Lindh Jan. 2, 1945 2,472,842 Mouchiroud June 14, 1949 2,761,855 Ham Sept. 4, 1956 FOREIGN PATENTS 693,792 Great Britain July 8, 1953 OTHER REFERENCES Uses and Applications of Chemicals and Related Materials, by Gregory, Reinhold Publishing Corp. (1939), pp. 611-613.

Industrial and Engineering Chemistry, article by Ericsson, October 1943, pp. 1026-30. 

1. A SPINNING SOLUTION FOR VINYL CHLORIDE POLYMERS COMPRISING POLYVINYL CHLORIDE DISSOLVED IN A MIXTURE OF TRICHLOROETHYLENE AND NITROMETHANE, AT A RATIO RANGING FROM 4 PARTS TRICHLOROETHYLENE TO 1 PART NITROMETHANE, TO 2 PARTS TRICHLOROETHYLENE TO 3 PARTS NITROMETHANE. 